Wednesday, April 27, 2011

VRT Rule Update for 04/27/2011

The Sourcefire VRT has identified possible issues with two shared
object rules. This release contains modifications to those rules that
fix these potential problems.

Details:
A problem has been identified in a shared object rule identified as GID
3 SID 18676. This problem causes Snort to hang in an infinite loop when
the rule is evaluated.

Mitigation:

1. The set of conditions necessary to cause this rule to enter an
infinite loop require a very unique set of content matches to be
present in the data being processed. In the unlikely event that
these conditions occur, the last content match in the set must not
return true.
2. This set of conditions is very unlikely to occur in normal,
non-malicious network traffic.
3. Additionally, if all the conditions in the rule are met, meaning
that a malicious set of traffic was detected, then the rule works
as expected and the infinite loop does not occur.
4. There are currently no known threats available publicly or in the
wild for this vulnerability.

Upon review of other custom shared object rule code, a similar issue was
found in GID 3, SID 17665. The VRT has pro-actively fixed that rule.

The modifications to GID 3, SIDs 18676 and 17665 are included in this release.

In order to subscribe now to the VRT's newest rule detection functionality, you can subscribe for as low as $29 US dollars a year for personal users, be sure and see our business pricing as well at http://www.snort.org/store. Make sure and stay up to date to catch the most emerging threats!